Contact assembly for plugboards



April 14, 1959 w. s. WATTS CONTACT ASSEMBLY FOR PLUGBOARDS 2 Sheets-Sheet 1 Filed Feb. 11, 1954 INVENTOR. William 5. Wads April 14, 1959 w. s. WATTS 2,882,508

CONTACT ASSEMBLY FOR PLUGBOARDS Fil ed Feb. '11, 1954 2 Sheets-Sheet 2 INVENTOR. I B c William SWaccs ,WvL-ka United States Patent CONTACT ASSEMBLY FOR PLUGBOARDS William S. Watts, Harrisburg, Pa., assignor to AMP Incorporated, a corporation of New Jersey Application February 11, 1954, Serial No. 409,603

5 Claims. (Cl. 339-18) This invention in general relates to plugboard assemblies for electrical accounting machines, computers, and the like and more particularly to an electrical contact assembly which provides circuit connections between fixed and movable plugboards of a plugboard assembly. For purpose of illustration the invention will be set forth in the present specification in association with plugboards and related parts such as are found in electrical accounting machines.

It has become the prevailing practice to provide in electrical accounting machines of the perforated record controlled type a fixed panel on which are arranged a multiplicity of electrical contacts in rows and columns, certain of the contacts being connected to the sensing elements or brushes of the machine and the remainder pro viding terminals for the leads connected to the instrumentalities that perform the operative functions of the machine under control of perforated records. A control panel cooperates with the fixed panel to provide a circuit connection between the electrical contacts and associated sensing elements and the instrumentalities desired to be operated according to some predetermined arrangement. To accomplish this purpose the control panel is provided with removable plugs or pin contacts whereby a pre-set arrangement may be made with the panel and contacts being removable as a unit from the plugboard assembly, a separate plugboard panel being furnished for each arrangement desired.

Generally the control panel is carried by a frame which may be pivotably connected to the fixed panel, pivotal movement of the frame bringing the panels into operative relationship. To distribute evenly the contact pressure throughout the assembly whereby to prevent warping of the control panel, it is preferable that the panels, or plugboards, first be brought to a parallel position with the two sets of contacts being in an overlapping equally spaced relationship. Subsequent movement of the movable panel along the fixed panel causes the contacts to engage simultaneously and effects even distribution of contact pressure. A mechanism for producing the movement of the panels, as described, is disclosed in US. Patent No. 2,594,737, issued April 29, 1952, to James M. Cunningham. The present invention is here described in a form suitable for incorporation in the structure disclosed in said Cunningham patent but other forms will readily occur to others skilled in this and related arts.

To render such a plugboard assembly practical, good electrical contact between the panels must be assured. It has been found, however, that merely bringing the control panel plugs into engagement with the fixed panel terminals does not sufiice due, among other causes, to contact failure resulting from the accumulation thereon of dust and films and by corrosion and pitting of the contact surfaces.

Accordingly, it is an object of the present invention to provide in a contact assembly for plugboards a spring contact which assures a clean and positive electrical contact.

2,882,508 Patented Apr. 14, 1959 ice Another object of the present invention is to provide a contact assembly for plugboards wherein the relative movement of the contact carriers is amplified as translated into wiping action between the contacts.

A further object of the present invention is to provide in a plugboard assembly a spring contact which is simple to insert and to lock in position in the associated contact carrier.

Still another object of the present invention is to provide in a plugboard assembly a spring contact of a durable single piece construction.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which:

Figure 1 is a fragmentary side view of a plugboard assembly with portions cut away to illustrate the relationship of the contact element of a contact assembly mounted thereon;

Figure 2 is a front view in elevation of the plugboard assembly with certain parts being broken away as indicated in Figure 5;

Figures 3a and 3b are side views of a spring contact for the fixed plugboard of the plugboard assembly;

Figures 4a and 4b are diagrams of the contact assembly as the contacts move into engagement; and

Figure 5 is a detailed fragmentary view illustrating the contact assembly mounted in the plugboard assembly.

Referring now to the drawings, there is diagrammatically illustrated in Figure l a plugboard assembly including movable plugboard 1 which is shown loosely pivoted at 2 to a fixed plugboard 3 adapted to be rigidly afiixed to an electrical accounting construction as by bolts 4. A mechanism (not shown) of a type well known in the art is provided to swing movable plugboard 1 about pivot 2 from the open position as shown to a position parallel to a fixed plugboard 3, and then to lift or move plugboard 1 along the fixed plugboard by a predetermined amount. Such means form no part of the present invention and hence are omitted for purposes of clarity, an example of a suitable mechanism being shown and described in the I. M. Cunningham patent referred to above.

Fixed plugboard 3 is provided, as shown in Figure 2, with a plurality of apertures 6 arranged in rows and columns which are adapted to receive a like number of contact members 7, some of which are coupled to the sensing elements of the machine while others are coupled to the various instrumentalities that perform the operative functions thereof. conventionally, movable plugboard 1 is provided with a removable panel 8 having a plurality of apertures 9, corresponding to apertures 6, in which cooperating contact members 10 are adapted to be inserted for the purpose of contacting members 7, as shown in Figures 4 and 5, of the fixed plugboard when the plugboard assembly is in the closed position.

Intersecting apertures 6 on the face of the fixed plugboard are longitudinal grooves 12, as shown in Figures 2 and 5, for a purpose to be explained hereinafter.

Member 10 is preferably in the form of a plug or jack and includes a barrel 13 which is detachably held to plugboard 1 in aperture 9 by any suitable means known in the art. For example, a friction grip between barrel 13 and the sidewalls of aperture 9 will sufiice, however, spring retention such as disclosed in U. S. Patent No. 2,056,361, issued October 6, 193 6, to A. W. Mills may be utilized if desired. A ferrule 14 integral with barrel 13 provides a means for attaching connecting lead 11 to member 10. The contact portion of member 10 is preferably in the form of a pin 15 which cooperates with the corresponding contact member 7, in a manner to be later described, to provide the desired electrical connection therebetween.

Figures 3a and 3b illustrate, in plan and side views respectively, the form of contact member 7 such as is aifixed to the fixed plugboard. As shown, contact memher 7 comprises a barrel portion 16 which is adapted to be received by aperture 6 of the fixed plugboard. Integral with barrel 16 is a leaf spring portion 17 having shoulders 18 that seat in the bottom of grooves 12 when the contact member is inserted in the plugboard to prevent barrel 16 from turning in aperture 6 when spring portion 17 is placed under tension. A contact surface, or tab 19, for member 7 is formed by twisting a part of the length thereof through approximately 45 relative to the length and plane of spring portion 17. To provide for the circuit connection of contact member 7 within the accounting machine, a tapered tab portion 20, integral with barrel portion 16, is of such a length so as to project from the under surface of the fixed plugboard. A tapered socket, generally designated at 21 in Figure 5, connects the tab 20 to the machine leads. Other types of terminals, however, may be utilized. For example, barrel 16 may terminate in a slotted tab through which the machine leads may be threaded and wrapped.

The method of inserting the contact member 7 in fixed plugboard 3 is best illustrated in Figure 5, the member being held in aperture 6 on one side by shoulders 18 engaging the plugboard within grooves 12. Additionally, it will be observed that barrel 16 is of a length sufficient to project from the under side of plugboard 3 whereby a slight deformation of the excess length, as by pinching, will securely lock the contact member in the plug board.

With reference now to Figures 4a and 4b, as the movable plugboard 1 is positioned parallel to the fixed plugboard, the pins and the contact tabs 19 assume the position as shown in Figure 4a in cross-section. Upon the movement of movable plugboard 1 along a fixed plugboard, pin 15 will initially engage tab 19 as shown in the dotted lines in Figure 4b, further lifting of the movable board causing the pin to wipe a path along the surface of the tab. At the end of the lifting stroke the contacts are maintained in contacting position represented by the solid lines in Figure 412. It is to be noted, however, as by comparison of the broken away sections A and B of Figure 2 in conjunction with Figures 4a and 4b, that the plane of spring portion 17 is maintained by grooves 12 in a plane which is substantially parallel to the direction of movement of the pin 15, while the face of contact tab 19 is inclined thereto. Accordingly, as leaf spring 17 is constrained to flex in a direction perpendicular to the plane thereof, the relative motions of the pin 15 and contact member 7 will be at right angles. The path of contact of pin 15 on tab 19 will therefore approximate the hypotenuse of a right triangle, resulting in a wiping action which is an amplification of the movement of the pin and movable plugboard. This amplified wiping action is effective to clear any dust, corrosion or other foreign matter from the ultimate point of contact between the pin and tab of member 7 and assures a point of good electrical conductivity therebetween.

The angle between the planes of tab 19 and spring portion 17 has been described as being approximately 45. This angle effects a path of wiping contact between the elements which is satisfactory for most purposes. It may be desirable, however, in view of other design considerations, for example to adjust the contact pressure between the elements, to increase or decrease slightly the magnitude of this angle. Since a reduction from an angle of 45 decreases the path of wiping contact, and hence decreases the self-cleansing action of the assembly, it may be preferable that such design considerations be resolved by other solutions, as by changing the flexibility of the material from which the spring contact is formed.

' While in the foregoing specification and drawings I have shown and described a preferred embodiment of my invention, it will be recognized by those skilled in the art that many modifications may be made without departing from the spirit of the invention which is not to be limited except insofar as is necessary by the scope of the specification and the appended claims.

I claim:

1. In a contact assembly for a plugboard assembly which includes a fixed plugboard provided with a plural ity of apertures and longitudinal grooves intersecting said apertures, a contact member for said plugboard, said contact member comprising a barrel portion adapted to be received by one of said apertures for mounting said member on said plugboard, a leaf spring portion integrally extending from said barrel portion having shoulders adapted to be received in said grooves for aligning said member on said plugboard, and a tab portion integral with said spring portion and set at an acute angle relative to the plane and about the length of said spring portion to provide an electrical contact surface on said member, the longitudinal axes of said portions being substantially parallel.

2. In a contact assembly for a plugboard assembly which includes a fixed plugboard provided with a plurality of apertures and longitudinal grooves on the front side thereof intersecting said apertures, a contact member for said plugboard, said contact member comprising a barrel portion adapted to be received by one of said apertures, said barrel portion including terminal means for cooperating with a lead brought to the back side of the plugboard and having a deformable extension adapted to project from the reverse side of said plugboard whereby to provide a retaining means for said member, a leaf spring portion integral with said barrel portion having shoulder portions adapted to be received in said grooves, and a tab portion integral with said spring portion and twisted through an angle of substantially 45 relative to the plane and about the length of said spring portion to provide an electrical contact surface on said member, the longitudinal axes of said portions being substantially parallel.

3. In a plugboard assembly including a fixed plugboard having apertures intersected by longitudinal grooves on one face of the plugboard, an electrical contact member for the fixed plugboard comprising an elongated leaf spring portion having shoulders adapted to be received in the grooves for maintaining the plane of said spring from rotation, a barrel portion at one end of said spring portion adapted to be received in an aperture and to protrude from the other face of the plugboard, the protruding part adapted to be deformed for locking said member on the plugboard, and a tab portion at the other end of said spring portion being twisted through an angle of substantially 45 relative to the plane and about the length of the spring so as to provide a contact surface engageable by a mating contact pin adapted to be disposed substantially parallel to said member and moved in a plane parallel to the plane of said spring portion for flexing said spring portion and wiping said contact surface upon interconnection of the assembly.

4. In a plugboard assembly including a fixed plugboard having a plurality of apertures therein, an electrical contact member for the fixed plugboard comprising an elongated leaf spring portion, a barrel portion at one end of said spring portion adapted to be received in an aperture and having means to lock said barrel portion within the aperture, means on said member adapted to cooperate with mating means on the plugboard for positively maintaining the plane of said spring from rotation, and a contact portion at the other end of said spring portion and set at an acute angle relative to the plane and about the lengh of said spring so as to provide a contact surface engageable by a mating contact pin adapted to be disposed substantially parallel to said member and moved in a plane parallel to the plane of said spring portion for flexing said spring and wiping said contact surface upon interconnection of the assembly.

5. For use in a ,plugboard assembly having a fixed board and a movable board adapted to be disposed parallel to the plane of and shifted linearly along the fixed board, a contact member for the fixed board for map erative engagement-by a contact pin carried by and proiecting from the movable board toward the fixed board, said contact member including an elongated leaf spring portion, means at one end of said spring portion for mounting said member on the fixed board with the longitudinal axis thereof directed toward the movable board and the plane of said spring portion parallel to the direcdisposition in the path of, and sliding contact by, the con tact pin.

References Cited in the file of this patent UNITED STATES PATENTS 1,369,221 Currier Feb. 22, 1921 2,120,396 Domaleski June 14, 1938 2,417,369 Luhn Mar. 11, 1947 2,594,748 Earl Apr. 29, 1952 

